The Liberal Democrats endured a particularly torrid night in the north of England, where left-leaning voters deserted the party in revenge for going into Government with the Tories. They lost all 10 seats they were defending in Manchester, 10 out of 12 in Hull, 10 out of 16 in Newcastle-upon-Tyne and nine out of 15 in Sheffield, where Mr Clegg is an MP.

In Liverpool, where the party lost 11 of 13 seats, its humiliation was heightened by the defeat of the former council leader Mike Storey at the hands of an 18-year-old Labour candidate.

The party lost an astonishing 23 seats to Labour in Chesterfield and six in Birmingham, which it runs in coalition with the Tories.

The Liberal Democrats' performance in the Scottish parliamentary elections was equally dismal: they managed to come first only in the island seats of Orkney and Shetland.

Their vote share halved to less than 8% in the first-past-the-post elections to Holyrood amid signs that tens of thousands of supporters had defected to the Scottish National Party. The Liberal Democrats drew some comfort from a better showing in a handful of southern councils, including Eastleigh, Bath & North-East Somerset and Portsmouth — all areas with high-profile Liberal Democrat MPs. As councillors represent the backbone of Liberal Democrat activists, the scale of the defeat is a savage blow to the party machine. Gary Long, whose six-strong group on Nottingham City Council all lost its seats, demanded Mr Clegg's resignation.

“Our chance of recovery will be better with a new leader,” he said. “He is carrying the baggage of decisions like that on tuition fees as well as the way he has run the coalition.”

There was little sign of a co-|ordinated attempt to oust Mr Clegg. But he will face intense pressure from MPs and activists to spell out more clearly the party's differences with the Tories and to demonstrate where it is having an impact on coalition policy.

The moment of maximum |difficulty for him is likely to be the annual party conference in September. A Clegg ally said: “We're really going to have to do a lot of reaching out to councillors.”

The Liberal Democrat blogger Mark Pack insisted: “The party's been in a worse state before and come back.”

But Benjamin Ramm, editor of The Liberal magazine, said: “This is not a gradual erosion of support but a collapse. In terms of councillors and voters, the Lib Dems are no longer a national party.”